Design education utilising digital fabrication is characterised by a dynamic project-based learning environment in which ideas are embodied in prototypes. This environment affects the way design and fabrication activities are taught, including sustainability considerations in the process and the outcomes. With the objectives of refining the sustainability indicators in the context of digital fabrication design education and identifying educational interventions for improving sustainability, we analyse the processes and outcomes of a digital fabrication course. We further develop a conceptual framework for sustainable prototyping based on the prototyping and testing stages in the design thinking model. The sustainability considerations in the prototyping process and outcomes in the design education context in FabLab are exemplified. The findings will help enhance sustainability and develop interventions in the context of design education.